Fractionation of lignocellulose materials-chc steps



1954 c. c. HERITAGE ET AL 2,697,702

FRACTIONATION OF LIGNOCELLULOSE MATERIALS- CHC STEPS Filed Feb. 9, 1951 STEP I Lignocellulose ["lorerial Wood Fiber 2 Sheets-Sheet l l:l Process Slap Treaf wilh Alkaline Reading i Compound of Alkali Melal lnrermediale i N H Producl l Exrracl wilh I Aaueovs Solven-l' STEP 11 Waler End mum Filler Treal' Wl'l'h Alkali Plelal HYPochIorire 1 mom Exlracl Wilh STEP m /J' Aqueous Solvenf- Wa'rer 24 2.2 m FlBER 11 Proce 55 for Conre nl Treal wirh Alkaline Reading as in Serial NQ3327B Com ound of Alkali Metal L H P+ i- N -Z 41 :o :=i 5 l NuOH J I Exlracl with /7 PS-I l Aqueous Solvenl Concen- 23 water fro-Te J2 EXTRACT ]I Process for Conlenl EXTRACT 111 as in Serial No.210234 Concen- INVENTORS CLARK C- HER/T1465 BY W/ LL/AM 6. VAN EEC/(UM A TTORNE Y5 1954 c. c. HERITAGE ET AL 2,697,702

FRACTIONATION OF LIGNOCELLULOSE MATERIALS- CHC STEPS Filed Feb. 9, 1951 2 SheetsSheet 2 I 1 NeuImIize and Concenfrare J6 ar PHT A"*I I H2504 I ?7 I Cool and Filfer Lignin 3-0, I i 3 46 I Z Add Alkaline Reading 43 I Maferial To Eouilibrium PH I I Cu(OI'II2 f Llme Cake '1 Fllfer @304 I Wash 2 Concernmre To Small VoIume 54H Ca'ke NaCI Nil-3 SO),

ConcQnIHlIe Furiher INVENTORS CLARK C. HER/ TAGE BY WILL/AM 6. WIN EEC/(UM POIYSacchQl'IdeS P5-5 I g ATTORNE Y5 FRACTIONATION F LIGNOCELLULOSE MATERIALSCHC STEPS Clark C. Heritage, Tacoma, and William G. Van Beckum,

Longview, Wash, assignors, by direct and mesne assignments, of one-half to Weyerhaeuser Timber Company, Tacoma, Wash, a corporation of Washington, and one-half to Wood Conversion Company, St. Paul, Minn., a corporation of Delaware Application February 9,v 1951, Serial No. 210,235

19 Claims. (Cl. 260-124) This invention relates to a process for the isolation of non-cellulose chemical products from lignocellulose materials with recovery of cellulosic fiber as an attendant product. More particularly the invention pertains to the separation of lignocellulose materials comprising cellulose, lignin, and polysaccharides-other-than-cellulose, into non-cellulosic substances, i. e., lignins, and other organics having a substantial content of polysaccharides-otherthan-cellulose and a cellulosic fiber residue of variable but controllable composition.

The invention is a continuation-in-part of our copending application, Serial No. 33,278, filed June 16, 1948, for Processing of Lignocellulose Material, now Letters Patent No. 2,541,058, granted February 9, 1951, and of our copending application, Serial No. 210,234, filed February 9, 1951, for Fractionation of Lignocellulose Material CH Steps.

The process of the invention is applicable to a diversity of lignocellulose materials, but is especially applicable to the fractionation of wood substance. Substantially all kinds of woods may be thus fractionated, representative and suitable woods being aspen, jack pine, western larch, Douglas fir, and many others. Substantially the same procedure and variations of it may be employed with all these varieties of woods, the results varying in degree.

In practicing the present invention, when wood is used as a source of lignocellulose materials, it is first reduced to finely divided or fibrous form by mechanical or other methods which do not subject the wood to the action of added chemicals other than water. Thus, wood fiber, sawdust, hogged fuel and similar forms of comminuted wood or lignocellulose materials are suitable raw materials for the practice of the invention. If the wood is fiberized, the fiberization is preferably carried to the point where it results in the conversion of substantially all of the wood substance to fibers physically consisting substantially of ultimate fibers and opened-up bundles of ultimate fibers, hereinafter all referred to as fiber, and constitutionally consisting primarily of cellulose, lignin, and other organics including polysaccharides-other-thancellulose, the latter being herein frequently referred to merely as polysaccharides, these three constituents being present in mutual ratios in the range of compositions from those characterizing the raw wood from which the fiber is derived to those characterizing the water-insoluble content of the raw wood from which the fiber is derived. Fiber containing cellulose, lignin, and other organics including polysaccharides-other-than-cellulose in the ratios characterizing the Water-insoluble content of the raw wood from which the fiber is derived, is exemplified by raw Wood fiber which has been so treated with Water as to extract the water-soluble constituents and leave as a fibrous residue the water-insoluble content of the raw wood. The production of such fiber from woods such as western larch, is of particular interest, since these woods contain high percentages of water extractable substances, e. g., about 23% in the case of western larch. It may therefore be commercially desirable in the case of these woods to extract them with water in order to isolate as commercial products the natural water-soluble fraction of the wood substance. A fiber form of the extracted wood may be employed to advantage as a raw material for the fractionation process of the instant invention.

The wood fibers to which the process of the invention States Patent 0 ice may be satisfactorily applied may be produced, for example, by the method described in U. S. Patent No. 1,913,607 to McMillan. This patent describes a mechanical defibering process entirely free from chemical action, which comprises combing out fibers from Wood by contacting logs of wood with high speed rotary radial elements, such as pointed pins projecting from an axle, like bristles. Fiber produced by this process is herein referred to'as McMillan fiber, or pin fiber, and it is an excellent raw wood fiber for the present invention. Such pin fiber may be processed with or without an initial water extraction.

Wood fiber suitable for use in the process of the present invention may also be prepared by the method described in U. S. Patent No. 2,008,892 to Asplund. In this method Wood substance is defibered by mechanically rolling and crushing the wood between relatively rotating opposing disks, while simultaneously applying steam under sufficient pressure markedly to soften the lignin in the middle lamella, thus permitting easy defibration of the softened Wood. The fiber resulting from this practice, in eflicient operation of the commercial Asplund machine, is termed herein normal Asplund fiber, or normal defibrator fiber. It is prepared, for example, by so defibrating the Wood while exposing it for about one minute to high pressure steam at a temperature sufiicient to effect the desired softening. The significance of the term normal is with reference to practical minimum operating time and temperature, as described, because increase of temperature or time has a chemical effect on the wood substance which may be measured in terms of water-soluble content formed by the action of the steam.

Any other process for reducing wood substance to said ultimate fiber or opened-up bundle form, may be employed. The wood substance may be affected by steam at any time or times before, during or after such defibration. Action by steam should be such as to avoid any substantial gasification of the wood substance which thus leads to loss or decomposition of wood substance, usually indicated by the formation of furfural, and evident in altered proportions of the three primary constituents, and by unduly altered forms of said constituents. Processes involving both defibering and steaming may be used. The fibers resulting from this process which includes those resulting from the Asplund process, differ from the raw wood in that their water-soluble content has been to a greater or less degree increased by the treatment with steam. In the case of normal Asplund aspen fibers made in about 1 minute at about 128 lbs. steam pressure, the increase in water-soluble content is about 4% to 5%, which is additive to a natural water-soluble content in raw aspen of about the same amount, variable, however, with the season of cutting and age of the tree. Thus, normal Asplund aspen fiber has about 8% to 10% of watersolubles.

Other methods for producing fibers from wood substance may also be used, provided said methods do not subject the wood to the action of added chemical agents other than liquid water or steam, or substantially alter the constituents in a manner other than those stated, excepting further, a treatment with an alkaline reacting compound of an alkali metal for the described purposes of the present invention.

Heretofore, lignocellulose material has been converted to pulp suitable for use in the manufacture of paper, fiberboard, and other products, by various mechanical and chemical methods, or combinations of such methods.

It is Well known, for example, to prepare paper-making pulp by treating raw wood with bisulfite salts, e. g., calcium bisulfite or magnesium bisulfite. It is also Well known to subject row wood to the action of numerous alkaline chemicals alone or in admixture, as in the well known soda, kraft or sulfate, and monosulfite processes.

None of these methods, however, has affected the precise By way of orientation, the present invention is part of a step-wise procedure devised for the carefully-controlled decomposition of lignocellulose material, particularly wood, into its various chemical constituents, including fiber or other lignocellulose residue. The total procedure comprises, with variations, three basic steps, outlined as follows: treatment with sodium hydroxide (caustic), sodium hypochlorite, and sodium hydroxide (caustic). The total process is, therefore, generally referred to as the CBC process, with the letters CI-1C standing for caustic, hypochlorite and caustic, and the lignins produced by the process are referred to as CI-IC lignins, Whether such lignins are produced by only one or all three of the basic steps. The three basic steps of the total process are also identified as Step I, Step II and Step III, and the products of each step are designated by corresponding numerals, as for instance Extract I, Fiber I and lignin 1 from Sept I; Extract II, Fiber II, and lignin 2 from Step II; and similarly for Step III. Our copending application Serial No. 33,278, of which this case is a continuation-in-part, which application has mateured as Letters Patent No. 2,451,058, dealt with the first of the three basic steps, i. e., the caustic or alkali treatment, identified as Step I and the corresponding chemical products. Our copending application, Serial No. 210,234 of which this case is also a continuation-.in-part dealth with the treatment through the first two basic steps, i. e., the caustic and hypochlorite treating steps, identified as Steps I and II, and also as the CH (caustic and hypochlorite) steps of the CHC process, and the corresponding chemical products. The present invention deals with the full process through all three basic steps, which is therefore sequential to our application Serial No. 210,234, including the further treatment of Step III which results in the formation of Extract III and Fiber III. The present invention also includes the processing of Extract III to obtain lignin products and a polysaccharide concentrate therefrom which are designated by the Arabic numeral 3 together with appropriate subclassifications.

It is a general object of the present invention to treat lignocellulose materials of nature for isolating on the one hand mutually separable lignins and organics including polysaccharides-other-than-cellulose, and on the other handa useful cellulosic product.

It is also an object of the present invention to separate lignocellulose materials into fractions together comprising isolated lignins, isolated organics including isolated polysaccharides other-than-cellulostt, and isolated cellulosic fiber of controllable quality.

In our copending application Serial No. 33,278, Letters Patent No. 2,541,058, there is described and claimed a method .of treating lignocellulose fiber of the types above referred to as the initial substance for treatment, by the action thereon of alkali metal hydroxide to provide a treated fiber identified as Fiber I, and a separable liquid, identified as Extract I, containing extractives derived from the initial fibers by the treatment. There are also described numerous process steps upon the separated liquid towin the said extractives. The fiber residue of the said treatment has utility as a special fiber, being composed of cellulose, lignin and organics, including polysaccharidesother-than-cellulose, but in new proportions as a result of removal of said extractives.

In our copending application Serial No. 210,234, there is described and claimed a method of using Fiber I as a row material for a second processing by the action thereon of a selective agent which solubilizes lignin in Fiber 1, therebyto secure a Fiber II and an Extract II, and also to process Extract II for winning extractives therein derived from Fiber I, so that by said invention Fiber I is converted to one or more products of lignin and a concentrate of organics including polysaccharides-other-thancellulose, and a new and useful fiber (Fiber II) of increased cellulose content compared with Fiber I.

The present invention aims to use Fiber II as a raw material for a third processing to secure a Fiber III and an Extract III, and also to process Extract III for Winning extractives therein derived from Fiber II, so that by this invention Fiber II is converted to one or more novel lignin products and a concentrate of organics including polysaccharides-other-than-cellulose and a new and useful Fiber III of increased cellulose content compared with Fiber II. Or in another View, the present invention contemplates the provision of a three-step chemical treatment of ligno- 4 cellulose material for the production therefrom of a fiber product and three different chemical extracts followed by the processing of the third chemical extract to obtain different chemical products therefrom.

It is a particular object of the present invention to treat said Fiber II with an alkaline reacting compound of an alkali metal solution, as a solubilizing agent, which concurrently removes from the fiber substantially the remaining content of lignin and other organics including polysaccharides-other-than-cellulose, and then to separate the resulting Extract III and the resulting Fiber III.

It is also an object of the present invention to process the resulting Extract III for separating one or more of the kinds of extractives contained therein.

It is also an object of the invention to process Fiber I to Fiber II to Fiber III which is substantially of technical cellulose grade.

It is also an object of the present invention to recover from Extract III one or more novel lignin materials and a concentrate of organics including polysaccharides-otherthan-cellulose, which may be accumulated with likeclasses of concentrates resulting from processing of Extract I and of Extract II, whereby the said accumulations and Fiber III of the present invention may represent substantially allv of the original fiber employed to produce first Fiber I and then Fiber II and then Fiber III.

Other objects and advantages of the invention will become apparent from the following description and explanation in connection with the appended drawings wherein process steps are shown in rectangular blocks, materials in process are shown in double-line curved enclosures, and end products are shown in single ring circles. Precipitates are shown in circles disposed laterally of the filter step by which they are separated, and solutions resulting from filtration steps are shown in elliptical enclosures. Alternative sequences and steps are indicated by broken lines. Preferred materials or reagents are shown at the lower right of each ring, block or .enclosure.

Figure l is afiow chart diagrammatically representing the practice of the process for the production of Fiber I and an Extract I product, the further treatment of Fiber I for the production of 21 Fiber II product and an Extract II product, and the further treatment of Fiber II for the production of Fiber III and an Extract III.

Figure -2 is a flow chart showing the processing of Extract III for the production .of a number of products of the invention.

GENERAL DESCRIPTION It has been found that the above and other objects of the invention may be accomplished by subjecting comminuted lignocellulose, e. g., wood substance in fiber forms, .to the action of a limited proportion of an alkaline reacting compound of an alkali metal in a strong or weak aqueous solution thereof, or in a solid form on moist fiber, separating a resulting solution from residual fiber using added 'water'if necessary or desired; treating the said residual fiber with an alkaline solution of a hypochlorite salt of an alkali metal; separating a second fibrous residue from the residual treating solution; and treating the said residual fiber with an alkaline reacting compound of an alkali metal, .separating a third fibrous residue from the residual treating solution, and separating lignin and organics including polysaccharides-other-than-cellulose from said residual solution.

More specifically stated, lignocellulose materials are fractionated in accordance with the present invention by treating such materials in comminuted form, either in aqueous suspensions, or in'moist conditions of the lignocelluloseparticles, with an alkaline reacting compound of an alkali metal, e. g., sodium hydroxide, at atmospheric pressure and at a temperature ranging from room temperature to an upper limit of atmospheric boiling point where aqueous suspensions are involved, or higher temperatures for the treatment of moist fibers, for a time sufficient substantially to complete to equilibrium the chemicalreaction between the alkali and the wood substance, thereby convertingsubstantially all that portion of lignin and organics including polysaccharides-other-than-cellulose which'are so convertible under the conditions of the reaction, from awater insoluble state to a water soluble state with'substantial residue of lignocellulose remaining insoluble, separating the water soluble matter from the insoluble residue, by Washing with more water, if necessary, thereby obtaining an extract containing the lignin and said organics; then subjecting to the action of an alkali metal hypochlorite salt the lignocellulose residue, either in an aqueous suspension, or, if in moist fiber condition, in the presence of sufiicient water Within the fiber to permit interaction with the alkali metal hypochlorite, thereby rendering soluble further quantities of lignin and polysaccharides-other-than-cellulose, separating the resulting lignocellulose residue from the resulting weakened or exhausted solution; and then subjecting the fiber residue to the action of an alkaline reacting compound of an alkali metal, thereby rendering soluble further quantities of lignin and polysaccharides-other-than-cellulose, separating the resulting lignocellulose residue from the resulting weakened or exhausted solution, and separating dis solved lignin and dissolved polysaccharides-other-thancellulose from each other and from the residual solution.

The alkali for Step I is used in any amount, expressed in terms of caustic soda, upwardly from that which leaves an alkaline extract under the conditions employed, usually about 2.5 parts to 100 parts of oven dry fiber, to a large amount, for example, an amount equal to the oven-dry weight of the initial fiber, i. e., 100 parts alkali to 100 parts fiber. The alkali may be used in dissolved form in suspensions of the fiber in water, or may be applied as a solid to moist fiber without a suspending quantity of water. The ratio of fiber to a liquid mass containing it is expressed as percent consistency. A 4% consistency as a slurry may be used, or modified to a higher consistency, such as a 50% consistency, which is represented by a mass of suitably moist fibers. To minimize the effect of strong causticity on the fiber substance, low usage of water accompanies low usage of alkali metal hydroxide, and high uses of each go together.

For example, a mass consisting by weight of 100 parts of dry fiber (oven-dry basis), 100 parts of water, and 8 parts of sodium hydroxide constitutes a moist mass. The reaction may be carried out over a range of temperature conditions: the ingredients may be mixed at room temperature, in which case the heat of reaction will raise the temperature of the reacting mass up to possibly 60 C. or 70 C. and the reaction goes substantially to completion in 10 to minutes; the caustic soda in solution form may be heated before mixing with the remaining ingredients; or the ingredients may be mixed and heated by subjecting the mixed mass to the action of steam, or even superheated steam at a temperature as high as 140 C. under atmospheric pressure for a period of about 60 minutes.

Regardless of the various ways in wh1ch the treatment is conducted, the initial fibers or lignocellulose particles become acted upon by the alkali to produce a mixture of residual fibers and a spent liquor, both being the products of reaction and extraction between the lignocellulose, water and alkali material.

The objective of the caustic or alkali treatment, which is designated in the drawings and frequently referred to herein as Step I, is to provide a fibrous residue as Fiber I and a solution as Extract I. The fibrous residue, Fiber I, may be Washed with water and is then subjected in a second step, designated Step II, to the act on of an alkali metal hypochlorite salt in solution WhlCh has a pH of from slightly alkaline, say about 7.5, to about 10.5. A preferred pH range is from about 8.0 to about 8.3. During the treatment with the hypochlor te, the pH drops from the original values on the alkaline side to slightly acid in the range from about 5.5 to about 6.5. There is thus produced by the hypochlorite treatment, Step II, a lignocellulose residue designated herein as Fiber II and a mildly acid residual treating solutlon, designated herein as Extract II. The Fiber 11 is next treated in Step III with an alkaline reacting compound of an alkali metal, typically represented by caustic soda. The treatment may be conducted with the fiber and alkali in aqueous suspension or with the alkali in solid form admixed with moist or dry fiber and superheated steam. The conditions for the practice of Step III, together with the processing of Extract III for its chemical content, will be described hereinafter 1n greater detail with reference to the drawings.

Description of Figure 1.Szep I Referring to Figure 1 of the drawings, it will be seen that the process of the invention is practiced by treating lignocellulose material 7, e. g., wood fiber, as the starting raw stock, with an alkaline reacting compound of an alkali metal as indicated at step 8. The alkaline reagent employed is typically exemplified by sodium hydroxide. The treatment is conducted at atmospheric pressure and at a temperature in the range from room temperature to about C. The time of treatment is variable, depending upon the type of wood being treated, but in general may be from 10 to 15 minutes up to about two hours, or such time as shows the interaction to be approaching completion. The reacted mass is extracted at step 10 to separate the soluble matter from the thus treated fiber.

Step 8, or steps 8 and 10, herein referred to as the caustic or alkali treatment, and sometimes herein referred to as Step I, extracts from the wood substance a substantial proportion of the content of lignin and of other organic materials such as polysaccharides-otherthan-cellulose, and leave a fibrous residue. Step 8 may be practiced by a batchwise procedure or by a countercurrent or recycling procedure as hereinafter more fully discussed. Water is usually employed as the solvent in step 10, but the water may also be admixed with minor amounts of other materials, e. g., water miscible organic solvents such as methanol, ethanol or acetone in order to contribute specific properties to the solvent or for specific purposes. Water alone, orwith such other materials admixed therein, is herein referred to as an aqueous' solvent. Steps 8 and 10 may be efiiciently combined when an aqueous solution of sodium hydroxide is used, but when moist fiber is treated with solid sodium hydroxide, or with solutions so concentrated as to amount to syrups, the separate aqueous extraction step 10 Will be necessary. The extraction step as discussed and defined herein is deemed to include the extracting effect of the aqueous solution of sodium hydroxide without resort to a separate aqueous extraction where the solution of sodium hydroxide is sufiiciently dilute to provide good extracting action.

The mass or slurry, with the treated fiber in aqueous suspension, is next filtered at step 12, or otherwise processed to separate the treated lignocellulose residue 13, herein arbitrarily designated as Fiber I from the soluble matter in the filtrate or solution 15 arbitrarily herein designated Extract I, which contains lignin and the other organic materials including the polysaccharides-otherthan-cellulose. A more extended discussion of the alkali treatment of Step 1, including variables thereof, is contained in our copending application, Serial No. 33,278, Letters Patent No. 2,541,058. Extract I may be processed as indicated at 16, in a manner described in our copending application Serial No. 33,278, Letters Patent No. 2,541,058, for isolation of a form or forms of lignin designated 17, which may be a composite product, lignin 1, or sub-divided products thereof termed lignin 1-a and lignin 1-b. Also, a liquid concentrate 18 is obtained, which is rich in polysaccharides (PS-1).

Decripiion of Figure 1.-Step II The fibrous residue 13 (Fiber I) resulting from the treatment of wood fiber with dilute alkali metal hydroxide solution in Step I is then subjected in step 20 to the action of an alkali metal hypochlorite solution. This begins Step II. The hypochlorite treatment may be conducted on either moist fiber or with the fiber in aqueous suspension. Functionally, the hypochlorite is a fractionating agent for lignocellulose by partial solubilization, in a manner analogous to the alkali treatment of Step I. The prototype or prototypes of the lignin products and polysaccharides fractionated out by Step II are solubilized relative to aqueous media by the action of hypochlorite, whether the action be regarded as chlorination or an oxidation. The solubilization and fractionation effect of the hypochlorite applies as Well to the saccharides as to the lignins. The reaction with the two classes of chemicals is concurrent. The alkali treatment of Step I renders soluble those organic materials which are most easily solubilized, but the Step I treatment reaches an asymptote beyond which further solubilization is negligible. The functional objective of the hypochlorite treatment of Step II is, therefore, to carry the solubilization of the wood substance further to remove a further quantity'of lignin and saccharide products which were resistant to solubilization by the alkali treatment. Just as in the case of the Step I treatment,

passing chlorine into a solution of sodium hydroxide is treated, as at about -C.,

substantial completion of the-step,

gamma the Ste'p 11 treatment reaches-an;'asymptoteandcango no further than-a-certain maximum removal. However,

its re'ady availabilityand its etficientaction.

The hypochlorite saltmay be acommercially available product, or, if desired, it may be prepared imme- =diately before use;

Thus, a sodium hypochlorite solution of the desired concentration may be prepared by sodium hydroxide having a pH of 11 to 12-until the precalculated quantity *of chlorine for the quantity of NaOHused has been absorbed or until the pH of the-alkali solution has been lowered to a value of about 8.0 to 8.3. The reaction ratio for the preferred pH, based on parts by weight, is about 100 parts of sodium hydroxide to 85 parts of chlorine. However, the pH of the hypochlorite solution "may range from values slightly, above 7.0 to about 10.5,

in which case the ratio of NaOH to chlorine will vary accordingly. The desired reaction ratio based on parts by weight, is about 100 parts of sodium hydroxlde to 85 parts of chlorine. The solution is preferably kept cold during this process, as by mixing ice therewith.

The amount of hypochlorite salt used is variable depending upon the type of wood being treated, lowcellulose woods requiring a greater amount of hypochlorite salt than those of higher cellulose content. For substantially complete action by hypochlorite salt, the maximum amount will vary with the wood species and w1th the previous treatment. The usage of hypochlorite salt; 1s herebyexpressed as the amount of sodium hydroxide equivalent of the hypochlorite salt'actually used. Thus,

an 80% usage signifies that for 100 parts by weight (dry basis) of fiber treated by hypochlorite-salt, 80 parts t);

W1 chlorine to effect the desired pH, and the resulting solution is employedon the fiber. The hypochlorite treatment usually does not require higher than an 80% usage. Jack pine and other coniferous woods require about a 70% usage, while aspen requires about a 35% usage, for where the original fiber is raw wood such as McMillan fiber.

The dilution of the hypochlorite salt solution and the consistency of the mass of fiber being treated to said solution are related by the above mentioned usage'of-hypochlorite salt. Thus, where the mass being treated 1s such that it may be stirred by anagitator in a contain ng vessel, a consistency of about 4% I is a practical operating consistency, meaning, that about parts by weight of fiber are present in 100 parts by weight of solution. Accordingly, an 80% usage of hypochlorlte salt at 4% .consistency designates that for every 100 parts by weight of fiber (dry basis) there are about2500partsof water, and that 80 parts of sodiumhydroxide equivalent have been used. In terms of sodium hydroxide used to form hypochlorite salt, the solution is 3.1% in strength by welght.

Although it is possible in the first step of the invention, i. e., the step in which lignocellulose fibers are treated with dilute caustic alkali solution, to fortify and recycle the caustic extract into contact with fresh wood fiber, thereby building up the content of extractrves by a sub stantial degree, it is usually not practicalto replenish and recycle the aqueous alkaline hypochlorite solution employed in the second step to accomplish a similar result. This is in part because of the mineral content of the 'solution and also because a considerable amount of organic 75 materials, which are present 'in the alkali metalhypochlorite salt solution after it has. been once used, react with and consume fresh hypochlorite salt which might be added thereto in order to build up the hypochlorite salt concentration to an effective degree, The operation is, therefore, preferably a single cycle operation; Asthe reaction of the hypochlorite with the llgn'ocellulose Fiber I proceeds, the hypochlorite is consumed, and the pH of the reaction mass is lowered until at the conclusion of the reaction, the reaction solution, Extract 'II has a pH on the acid side, usually in a range from 5.5 to 6.5.

fiber may 'vary throughout "a wide range. I of from 4% to 25%, i. e., 4-'parts by'weight of'fiber per 1 The consistency of the mixture of hypochlorite and 'Co'nsistencies 'IOO'PaIfiS'Of solution to 25 .parts by-weight fiber per '100 parts solution, have been satisfactorily'used. -Consisteneiesin aqueous suspension up to 15% may besatisfactorily-er'nployed for the hypochlorite treatment,-but the use'of consistenciesabove 15% with aqueous suspension results in the product of a non-uniform Fiber II-p'roduct,

whichmeansgof course, that the-chemical content of'the wood is not being uniformly'extracted, and that the yield and identity of the chemicakproducts obtained from the solutionwill vary in agreaterdegree.

'Treatment with consistencies above 15% should be effected by spraying the hypochlorite solution in a strong jet onto a moist or dry fiberwhile 'vigorously mixing the same in order to insure uniformityof treatment. Under such conditions a usage 'of 35% sodium hypochlorite solution has been used with a consistency of 25% to produce a high quality Fiber II. A'typical,.preferred treatment is that of spraying ahypochlorite solution. on moist fiber so as to provide a consistency and a 20% usage of hypochlorite. salt. The reaction'is continued for from 15 to 30 minutes. The advantages of the more dilute versus the more concentratedconsistencies are-substantially similar to the advantages discussed herein connection with the variables of the alkali treating Step I.

. Treating times for Step II of from 15 to ZO-minutes up to about one hour usually effect substantiallywcomplete removal ofthe wood content susceptible to removal by the hypochlorite solution, with little furtherac'tion being observed during more protracted treatments. The. proper time within the range mentioneddepends on various factors, but principally on the consistency and .usage employed, which in turn determine the temperaturerof' the reaction. The temperature of thehypochlorite salt treatment may vary over a wide range, for example from below normal room temperature up to at least 75 C. Higher temperatures up to the boiling point of the hypochlorite solution may be used under some conditions.

Superatmospheric pressures, and the temperatureswhich accompany such pressures are avoided at all times,-as such pressures and temperatures would cause excessive degradation of the fiber residues and the chemical; products of decomposition. In other words, it is essential tothe carefully controlled decomposition of the lignocellulose in accordance with the principles of the present invention that each treating step be conducted at atmospheriepressures.

v The exothermic heat of reaction -is sufiicient to raise the temperature from room temperatures to 60. to 70 C., and the mixing is continued until the mass cools to-a temperature ofapproximately C. which is usually'from about minutes to lhour in the case of treatment in aqueous suspensions. Where the spraying technique is used, the reaction is substantially complete in 15 to 20 minutes.

Temperature variously affects the, treatment as to extracted content and as to the, propertiesof the residual fibers. The higher the temperature the more polysaccharides-not-cellulose are removed from the fiber. Where the residual fiber is to be used in making fiber 'boardor paper, it is preferred to operate at a temperature below 40 C. Temperatures lower than 25 C. have been used satisfactorily, and chilling to below room temperature has been practiced. When it is vdesired to limit the rise in temperature, the treatment. may be conducted in the presence of ice or in refrigerated apparatus. As pointed out hereinbcfore, the sodium hypochlorite solution is preferably kept cold during its formation by chilling with ice. It is therefore convenient to use this solution in its chilled condition, directly as formed.

Although the hypochlorite treatment removes larger amounts of polysaccharides-other-than-cellulose as the temperature of the treatment is-increased, the-over-all extraction by the hypochlorite salt, together with the subsequent alkali treatment of Step III, is substantially the same regardless of the amount extracted by the. hyporesidue is separated from the spent hypochlorite solution. Ordinarily the consistency of the mass during the hypochlorite treatment will be su ."ficiently low that the water of solution accomplishes simultaneously with the treatment the extraction of the chemicals rendered soluble by the treatment. This step is separately indicated at 21, however, to portray the function. When the consistency of the hypochlorite treating solution is quite high, the separate aqueous extraction step 21 is necessary, as illustrated. Where the separate aqueous extraction step is to be performed, the aqueous solvent may be the wash water from like fibers of a previous batch. Separation of solution 23 (Extract II) from the fibrous residue 24 (Fiber II) is most practically done by filtering as shown at step 22, but other methods of separation may be employed.

The extraction step as discussed and defined herein is deemed to include the extracting effect of the aqueous solution of hypochlorite salt without resort to a separate aqueous extraction where the hypochlorite solution is sufficiently dilute to provide good extracting action. When a separate aqueous extraction step is conducted, water is usually the extracting solvent employed, although wash waters may be employed as pointed out above. To the water, there may also be added minor amounts of other materials, e. g., water miscible solvents such as methanol, ethanol or acetone, in order to contribute specific properties to the solvent or for specific purposes. Water alone, or with such other materials admixed therein, is herein referred to as an aqueous solvent. The fiber residue 24 is then further treated in accordance with this invention as described hereinbelow in connection with the description of Step III.

The solution 23 from the hypochlorite treatment, Extract II, may be processed in accordance with the disclosure of application Serial No. 210,234, as indicated at 25, for the recovery of lignins 26 and a polysaccharide concentrate 27. The lignins may be any of the products, lignin 2, 2-a, 2-al, 2-a-2, and 2-17, as disclosed in our copending application Serial No. 210,234 and the polysaccharide product is the PS-2 product of said application.

Description of Figure 1.Step III Fiber II, as intermediate product 24, is then subjected to the action of an alkaline reacting compound of alkali metal, thus beginning Step III, as indicated at 30. Preferably, sodium hydroxide is employed. Functionally, this treatment effects dissolution of resistant forms of lignin retained by Fiber II, and also the dissolution from Fiber II of polysaccharides which are acted upon at this point to permit such dissolution, the action having been effected primarily in the treatment of Fiber I with alkali metal hypochlorite.

The Step III treatment may be conducted under the same range of variables and with the same range of materials as used in Step I, as is fully described in our copending application, Serial No. 33,278, Letters Patent No. 2,541,058. For instance, the Step III treatment may be either in dilute aqueous suspension, or it may be a treatment of moist fiber with the alkaline reacting compound of the alkali metal in solid form. The selection of the particular consistency, usage, and type of treatment is optional with the operator, and dependent upon the facilities and equipment at hand. Other things being equal, it is preferred to use the alkaline reacting compound at lower strengths, usually not exceeding 1%, in order to effect the extraction without undesirably altering the residual fiber or substantially changing the composition of the extracted materials. For the purpose of stating a preferred embodiment, the following description of Step III will be with reference to using a sodium hydroxide solution having a 0.4% strength. Whatever alkaline reacting compound is used, is employed in a quantity sufficient to furnish, and at whatever strength, an amount, in terms of caustic soda, which is equal to about parts by weight to 100 parts of Fiber II (dry wood) treated thereby. In order to provide an easily workable slurry, it is preferred that the consistency be about 4%.

The temperature for the operation is preferably maintained at a relatively high level during the extraction in order to effect the desired dissolution of the lignin and polysaccharides. A temperature which is substantially the boiling temperature of the treated solution at prevailing atmospheric pressure is the preferred temperature. For any atmospheric pressure a boiling temperature is preferred largely for simplicity of control and for standardized operations.

The time of treatment is preferably standardized also for simplicity at approximately 1 hour. Little advantage is gained by longer periods, and the desired action may be entirely completed in much shorter times. However, the time is not critical, because at any time which is chosen, there is a degree of extraction giving results in degree up to the maximum obtainable. In many cases, times considerably less than one hour are sufficient to complete the desired extraction. Fiber II, time, temperature, usage of alkali metal hydroxide, strength of the hydroxide solution, and consistency, are all variables and in part are dependent factors.

When the extraction is carried out at high consistencies, 't is desirable to effect dilution before separation of fiber 1nd extracting liquor. Water may be added to dilute he extraction mass, or washings from previously separated similar fiber may be employed in the dilution. Such dilution is indicated at step 31, and it is of course, understood that this step may be omitted. The same con gideration for the aqueous solvent apply as in step 10 of top I.

Then, the fiber from step 30, or from step 31, is effectively separated at 32 by filtering or other suitable means to provide residual fiber product 33, designated Fiber III, and to provide a liquor 34, designated Extract III. The residual fiber 33 may be washed with water if desired, and the washings used in step 31 as indicated. Fiber III may be used for a diversity of purposes, such as making paper, or as raw material for further chemical refining. It is an excellent fiber for mechanical treatment to form a cellulose gel as a binder in the manufacture of felted cellulosic products.

The liquor 34 is preferably recycled through Step III, after being fortified with additional alkali metal hydroxide, in amount to bring the extracting solution back to its original alkalinity, for example, in the case of sodium hydroxide, to the preferred 0.4%. The amount of fortification which is necessary is variable depending upon the extent to which the treating solution has been exhausted during the extraction step. This in turn depends upon the kind of Fiber TI employed, which is turn depends upon the extent to which Step II may have been practiced, as well as upon other factors, obviously variable. In general, however, in the case of sodium hydroxide. a suflicient quantity is added to replace about 60% of the original sodium hydroxide content of the solution. The extracting solution may be thus replenished and recycled for the extraction of succeeding batches of Fiber I for a total of at least 8 extractions, or until there is little further gain in extract concentration. The recycling of the treating solution or its equivalent use. as in the case of a counter-current flow, may be carried on to advantage in Step T, in the same m nner as in Step I, as long as more substance is extr cted from Fiber T b the solution than is mechanicall he d thereby at the final se aration of Fiber I" and Extract I I. In thi manner the concentraction of diss lved li ru'n and pol sacch rides is built up in the extracting s l ti n until such solution becomes a worthwhile source of these substances.

Then, Extract H is used as a raw material for separation, as indicated at 35, into valuable lignin pr ducts and a polysaccharide product, as more particularly illustrated in Figure 2.

Description of Figure 2.Treatment of Extract III In accordance with the plan outlined in Figure 2, Extract III (34) is neutralized and concentrated while maintalmng 1t neutral at step 36. Since Extract III is alka ine and has a pH of about 10 in the case of sodium hydroxide, its neutralization is effected by the addition of a quantity of a suitable acid sufficient to reduce the pH value of the solution to about 7.0, preferably an inorganic acid having the radical HSO4. This may be sulfuric acid or an acid sulfate salt, such as sodium bisulfate. Of course, other acids may be used, but acid with the sulfate radical is preferred to facilitate removal of the acid radical in the subsequent operations. All that is functionally required of the acid is that it have an ionization potential sufi'icrent to provide the desired pH values for precipitation of lignm, as will hereinafter be specified. Also, the acid assume.

11 should be of suchanature as to avoidintroducing contaminating chemicals.

If lignin is precipitated during this concentration step 36, or, when the concentrate therefrom is cooled at any final stage of concentration, the-solution is filtered as indicated at 37, and preferably filtered cold for recovery of av greater quantity. of lignin than when filtered hot. The, separated. solid lignin is recovered as product 38 and. designated lignin 3-a. The residual liquor from the filtration, or. the original concentrated solution if no, lignin precipitates at pH 7, is acidified, preferably with sulfuric acid,- to apH. of 1.5 indicated at step 39. Thisacidification may be-carriedout stepwise, if desired, filtering after each addition ofacid which is-etfective to lower the H and cause precipitation of a ligninmaterial, which precipitates atany specific pH. For example, the acid may be addedto effect a pHof 5.0 and the. slution filtered to remove any precipitated lignin as, a separate lignin product which is then designated lignin 3-b,l.. Thenthe residual, acid solution isfurther. acidified to apH; of 1.5, thereby causing the-separation of a further quantity of. lignin which is recovered as aseparate ligninproduct designated lignin 3b2. Thus, the lignin which is precipitated from a pH of 7 to a PH. of L may be recovered. by filtration. at.- step 43 as oneeomposite lignin product 3b- (44), or. as a plu ralityof separate lignin products, each having'itsown different chemical, properties.

Since the extract may contain an appreciable quantity of volatile acids, principally the lower molecule weight organic acids, such as formic acid. and acetic acid, itmay. be desirable in commercial operation to recover such of theseas are volatile; This may be accomplished as indicated at step40 by steam distilling the acidified. solution to recover the volatile acids.41. This steam distillation is optional, however, as indicated. byv the broken line 42 by-passing the operation and leading to. the filtration step 43. In step 43 the precipitated lignins of thelrquor either before or after steam distillation 40 arefiltered otf toprovide solidlienin-3-b designated 44, and providing, aliquor 45 at a pH of 1.5.

The residual acid, liquor 45, now substantially free from lignin, is then neutralizedas shown at.46, .by the addition of an alkaline reacting-material, preferably of the group consisting of-hydroxides, oxidesor carbonates:

of. an alkaline-earth metal, in an amount sufficient to.

bring the pHto equilibrium in order to neutralize the ac1d1ty of .the solution and thus facilitate its further processing, storage-and handling.

than acidic solutions, andalso avoid corrosion of metal containers to a much greater extent. Hydrated calcium. hydroxide 1s the preferred reagent, as its use avoids excess heat-orthe formationof carbonic acid gas. effected by Neutral or slightlyalkaline olutions presentmuch less rocessingdifiiculties off, the dissolved carbon dioxide. While, ordinarily,.

the neutralization pH is 7.0, it will be, found:that .an.

equilibrium pH ranging from 7.0 to about 8.5 may be obtainedat this.step, due to the presence of salts of Weak acids. When the salts of the alkaline materials employed in step 46 are soluble, as, for example, .when. sodium hydroxide is used, the inorganic salt content ofthe final solution is increased.

The lime cake 48 .may bewashed with water as shown at step49 for recovery of occluded organic materials. The washwatersare then combined with thefiltrate 50.from filtration step 47. The filtrate stillj includes, in addition'to its polysaccharide and otherorganiccontent, a ,substantial quantity of sodium or other alkali salts.

A. .further .amount of the inorganic. content. of the filtrate from filtration step 47 may-then beremovedby concentrating the solution to a smallvolume as shown at. stepSLthereby etfectingthe crystallization 0ft inorganic salts, such as sodium chloride and. sodium. sulfate as the salts obtained when sulfuric. acid,;is used as the acid material.

12 acidifying agent at step 49. The crystallized. inorganic salts are then removed as salt cake 53 by filtrationatstep 52. Separation of the sodium sulfate as a solid'is facilitated by the technique known as freezing out in which the solution is cooled prior to filtering to lower the solubility product value of the sodium sulfate. Further concentration of the solution at step 54 results in the production of a solutionof organics including polysaccharides, product 55, designated as PS-3, which may be used without further treatment as a source of polysaccharides, or which may be processed further to separate solid polysaccharides therefrom.

Modifications cellulose materials. Or, again, the'process may be modifiedwhen it-is desired to obtain all the lignin content as a single product. Such a modification is indicated byalteruative sequence A in Figure 2, which indicates that the Extract III may be taken directly from-a pH of' 10' toa pH of about 1.5, by theaddition of a suitable As a resultof such direct loweringof the pH to 1.5, all the lignin content will be precipitated in a single composite product, which may --be designated lignin 3,-since it contains both the products lignin 3-0- andlignin -3b. It may be desirable in the course of taking the pH directly to 1.5 toconcentrate the solution in order to improve or provide the necessary precipitation characteristics for the lignin.

Similarly, the process may also be modified by first practicing steps 36 and 37 as described in Figure 2 to produce lignin 3-a, and then making further additions of acids stepwise to a plurality ofsuccessively decreasing values in-therange fr0m-7 to 1.5, and filtering oil at any such pH any lignin which precipitates thereat. In the, scheme of the nomenclature devised, such lignins would be identified as lignin 3-b-1, lignin 3b2, etc.

Alternativeprocedures are also possible, or may be necessary, in the treatment of the liquor 45 (referring to Figure 2), to obtain a purified polysaccharide product, PS-3. In the event an acidhas beenemployed other than sulfuric in the steps of the process prior to the production of the liquor 45, whose anion can appropriately be precipitated by a suitable reagent, such reagent may be used, either alone, or inadditionto an alkaline reactiugmaterial specified for use at step, 46.

In the event the acid radicalzemployedin the steps of the processprior to the production of liquor 45 cannot be precipitated or eliminatedby the additionof a suitable reagent as at step 46, the solution may be treated'bythe alternative procedural sequence B.. The organic salt content may be substantially removed, asindicated by.

steps 51 and 52, by the employmentof a concentration by evaporation procedure ora freezing out technique, whereby the solution is first concentrated .to a small volume and then cooled, thereby causing, the inorganic salts to crystallize outof the solution, after Whichthey may be,

removed by filtration.- A combination.of concentration and freezing, out. techniques vmay be employed. By freezing outFis-meant the lowering of. the temperature of. the solution to a:value at which the inorganic salt.

content becomes relatively insoluble, thereby causing it to crystallize from solution. The salts which thus crystallize out are filtered at step 52Land recovered as a salt cake 53-.leaving the filtrate as a syrup consisting of a substantially'pure PS-3 product.

Preferred embodiment A preferred process of the invention is illustrated in the following examples as appliedto different species of wood. The yields and composition of the products obtained are summarized in tablesfollowingthe'examples.

EXAMPLE 1 This resulted. .in a reaction mixture havingaconsistency of about.4-%.

moved from the wood substance,

i. e., a mixture containing about 4 parts by weight of fiber per 100 parts of solution. The treatment was effected at the boiling temperature of the solution at atmospheric pressure for a duration of one hour. The fiber was then separated from the sodium hydroxide solution and washed with Water for subsequent uses. The alkaline extract was fortified by the addition of caustic soda in an amount sufficient to build up the sodium hydroxide concentration to a level substantially that of the original solution. This required replacement of about 60% of the original sodium hydroxide. The fortified solution was then employed in the treatment of a further quantity of raw wood fiber. A total of 8 treatments of raw wood fiber was carried out in this manner, replenishing the concentration of sodium hydroxide in the treating solution between each treatment. This resulted in the production of an alkaline extract rich in materials rei. e., rich in lignins and in polysaccharides-other-than-cellulose.

This alkaline extract was processed for the recovery of its lignin and polysaccharides-other-than-cellulose content, substantially in accordance with the process described in copending application Serial No. 33,278, now Letters Patent No. 2,541,058. The separation of these substances from the solution and from each other was accomplished by neutralizing with sulfuric acid the alkaline extract, which had a pH of about 10 to a pH of about 7, and concentrating the neutralized extract by evaporation while adding further sulfuric acid as necessary to maintain the solution neutral. The solution was thus concentrated to about 12% of its original volume. It was then cooled and filtered. This resulted in the separation of a lignin fraction designated herein as lignin 1 a.

The neutral solution remaining after the separation of lignin 1a was then acidified with sulfuric acid to a pH of about 1.5, sufficient sodium sulfate being added to satisfactorily coagulate the lignin, forming a s olut1on saturated or partially saturated with respect to this compound. The acidified coagulate was then steam dlstlllfid to separate volatile organic acids, after whlch it was filtered n order to separate lignin 1-b.

Suificient lime was added to the liquid remaining from the separation of lignin 1h again to bring the pH of the solution to a value of 7.0, thereby neutralizing the excess free mineral acid and at the same time formmg a precipitate of calcium sulfate (lime cake), corresponding 1 n amount to an equivalent weight of the neutralized sulfuric acid. After removal of the calcium sulfate by filtration the liquid was concentrated to a small volume cooled and filtered to remove in the form of a crystalllzed salt cake the remainder of the sulfate radical which was present in the form of molecular sodium sulfate. This left a syrup containing organic bodies including polysaccharides-other-than-cellulose.

The Fiber I residue remaining after the alkalme extract, carried out as described above, was next treated with a solution of sodium hypochlorite. The sodium hypochlorite solution employed in this treatment was prepared by passing chlorine gas into a solution of sod um hydroxide which contained a sufliclent amount of sodium hydroxide to be equivalent to 35% by weight of the fiber residue to be treated. Chlorine gas was passed into this solution until the pH of the solution was decreased from about 11 to 12 to about 8.0 to 8.3. This required the reaction of the sodium hydroxide with approx mately an equal weight of chlorine. The reaction mixture was cooled with ice during this addition. A sufficient amount of this solution was used in the treatment of the fiber to form a mixture having a consistency of about 4%, i. e., one containing about 4 parts of fiber per 100 parts of solution. w

The fiber was treated with this solution for about one hour at a temperature of about 25 C. At the end of this time the mixture had become acid, the final pH being about 5.5 to 6.0. The spent solution was separated from the fiber, the fiber being washed with water and as F1ber II applied without further processing to a d1vers1ty of uses, or if desired used as a starting material for further refinin ste s.

Tl'ie acid hypochlorite extract (Extract I I) obtained from this extraction was neutralized w th sod um hydroxide and concentrated to about 12% of its orig nal volume. It was then cooled and filtered to separate l1gn1n 2-a-1.

The filtrate was concentrated further to about 6% of its original volume. It was then cooled and filtered to separate lignin 2-11-2. The filtrate remaining after removal of lignin 2a-2 was acidified with sulfuric acid to a pH of about 1.5 and steam distilled to separate volatile acids, after which it was filtered to remove lignin 2-b.

After removal of lignin 2b, the solution was brought to a pH of 7 by the addition of lime, and filtered to remove the precipitated calcium sulfate. Thereafter it was concentrated to a sufiiciently small volume to effect the precipitation of a substantial proportion of its sodium chloride content. This was removed by filtration, and the solution further concentrated to yield a syrup rich in organics including polysaccharides-other-than-celluose.

The final residue remaining after the extraction with sodium hypochlorite solution was next extracted with dilute sodium hydroxide solution. This treatment was carried out by means of mixing about 4 parts by weight of the said fiber (dry basis) with about parts by weight of a 0.4% solution of sodium hydroxide. This provided sufficient sodium hydroxide to equal about 10% by the dry weight of the fiber treated, and it provided a slurry at approximately 4% consistency. The extraction was carried out at the boiling temperature of the solution for approximately 1 hour. At the end of this time the fiber residue was separated from the extract, and the latter was replenished with a 60% replacement (based on the original amount used) of sodlum hydroxide, and recycled for a like treatment of a further quantity of fiber. This solution was thus recycled for a total of 8 extractions.

The fiber resulting from the above treatment (Fiber III) was washed with water and applied to the manufacture of paper and the production of chemical cellulose, or alpha cellulose, by use of stronger sodium hydroxlde solutions. The sodium hydroxide extract solut1on which at a pH of about 10 was processed for the recovery of the lignin and polysaccharides-other-thancellulose. The said solution was first neutralized with sulfuric acid and concentrated to about 12% of its original volume while maintaining it at approximately a pH.

of 7, by the addition of sulfuric acid as required. This procedure did not effect the precipitation of lignin in thls particular example, using the particular species of llgnocellulose. Consequently, no lignin 3-a was recovered. The solution was then acidified with sulfuric acid to a pH of 5.0, and no appreciable amount of lignin was formed, up to this point of acidification. The solutlon was then further acidified with sulfuric acid to a pH of which caused the precipitation of lignin. acidified llquor containing the lignin was then steam dist lled to remove volatile acids. After the steam distillat1on, the solution was filtered, thereby effecting the separation of lignin 3-b. Lime was then added to the res dual solution to a pH of 7, thus causing the precip- 1t at1on of calcium sulfate which was removed by filtratlon. The filtrate was then concentrated to a small volume, thereby precipitating inorganic salts, notably sod1um sulfate, which are filtered off. Further concentration of the residual solution effected a syrup contaming polysaccharides.

EXAMPLE 2 Fiber prepared from aspen wood by means of the Asplund defibrator wherein the wood is subjected during defibration to the action of steam at about 128 to pounds pressure per square inch gauge for about 1 mmute was also treated successively with dilute sodium hydroxlde solution, then sodium hypochlorite solution, then again sodium hydroxide solution, and the extracts processed, all substantially as described in Example 1.

EXAMPLE 3 McMillan Jack pine fiber was also treated with dilute sodlum hydroxide solution, then with sodium hypochlor1te solution, and then again with sodium hydroxide solution, and the extracts separated into lignin and organic fractions, all substantially as described in Example 1. In this case, however, because of the low cellulose content of the fiber employed it was necessary in Step II to use an amount of sodium hydroxide for the hypochlorite formation equivalent to about 70% by Weight of the fiber used rather than about 35% as was the case in Example 1.

The-

is EXeM 4 Fiber was prepared from Jack pine by means of the Asplund defibrator wherein the wood was subjected during defibration to the action of steam at about 150 pounds per square inch gauge pressure (365 F.) for about-1 minute and was then treated by Steps I, II and III,.Iand the three extracts processed as described in E7.- aInple 1. In this case, as in Example 3, a usage of about 70% of sodium hydroxide'ba'sed on the weight of fiber treated was employed for the reagent of Step II.

The yields of the' various products obtained by the application of the alkali treatment, Step I, of the process ofgthe invention to the various types of wood fibers, as described in the foregoing examples, may be summarized as follows:

Table I YIELDS OF PRODUCTS FROM STEP I [In percent by weight of original fiber.]

M r-Millan Asplund M QM illan Asplund Aspen Aspen Jack pine Jack pine (Example (Example (Example (Example 1) 2) Product:

Flb'er I 81. 3 79. 6 84.1 78. 9 Extract I (Difh); 18. 7 20. 4 15.9 21. 1

COMPOSITION OF EXTRACT I gn 5. 5 6. 1 3. 5 6. 5 Total Polysacchandes 5. 1 6. 8 6. 7 7. 1 Volatile Acids. 5. 8 5. 9 2. 9 4. 4 Total Organics Recovered.... 16. 4 18.8 13.1 18.0 Remainder Unaccounted For. 2. 3 1. 6 2. 8 3. l

The yields of the various products obtained by the operation of the hypochlorite treatment, Step II, on Fiber I, i. 'e., the fiber residue remaining after extraction of wood fiber with dilute sodium hydroxide solution, are summarized in Table II.

The initial total organics content 01 Extract II is determined by dlfierence.

The increase in the total organics recovered is probably due to combined chlorine.

The yields of various products obtained by the operation of Step II on Fiber II, in the four examples given above are summarized in Table 1H:

Table III YIELDS OF PRODUCTS FROM STEP III [In percent by weight of Fiber II] McMillan Asplund McMillan Asplund Aspen Aspen Jack pine Jack pine (Example (Example (Example (Example Product:

Fiber III 83. 1 87. 8 72. 7 81. 1 Extract III 16. 9 12. 2 27. 3 18.9

COMPOSITION OF EXTRACT III Lignin 3-b 3. 2 1. 4 11. 5 4. 4 Total Polysaccharides 8. 0 7. 7 10.7 10.3 Volatile Acids 1. 5 1.8 0.9 1.0

Total Organics Recovered... 12. 7 10. 9 23. 1 15. 7

Loss 4. 2 1. 3 4. 2 3. 2

The compositions, in per cent by weight, of original fiber, Fiber I, Fiber 11, and Fiber III, are shown in Table IV:

Table IV FIBER COMPOSITIONS BY WEIGHT Original Fiber Fiber I Fiber II Fiber III Pgrfient Peiclrlcnt Perdtlrlent Pgigrlzlent 1: er er cr er Percent Percent Percent Percent Organics Organics Organics Organics Lgmn Not Cel- Lgnm Not Cel- Llgmn Not Cel- Llgum Not Cellulose lulose lulose lulose McMillan Aspen (Example 1) 20.1 21.6 20. 0. 22. 4 l. 8 23. 8 0.29 22. 2 Asplund Aspen (Example 2) 20. 8 21.8 18.5 20.0 1.1 21. 7 0.29 19. 5 McMillan Jack Pine (Example 3). 29. 6 15. 1 29. 6 14. l] 6.2 9.0 0.80 7.0 Asplund Jack Pine (Example 4)... 29.6 13.6 30. 4 9.0 2.8 7. 4 0. 12 6. 7

Table II YIELDS OF PRODUCTS FROM STEP II [In percent by weight of Fiber I.]

PAPER-MAKING QUALITIES OF FIBER III It is also an advantage of the instant invention that high quality paper-making grade cellulose is obtained in high. yields by; the application to. wood fiber of Steps, I, II and III. Since the conditions of treatment are carefully con-. trolled and the concentrations of the reagents are relatively weak, the resultant fiber has properties making it an improved fiber for use as a paper-making stock. This is true even though aspen wood is used as a source of fiber. The Fiber III produced from aspen Wood is produced in yields of the order of 5 3 based on dry. weight of the,orig i-. nal fiber, as compared with yields of only about 38% ohtainable by the usual commercial sulfite process.

TheFiber III; obtainedfrom aspen wood by. theprocess of the invention may be used in the preparation of a satisfactory commercial grade of paper without admixture with longer fibers derived from Woods of different species. It is thus possible to prepare on a commercial scale an all- Aspen paper by conventional hydrating and felting methods. This desirable result doubtless stems from the ability of the aspen fiber produced by the process of the invention to hydrate rapidly during milling so that long milling periods with resultant shortening of the fiber lengths are not necessary during the paper-making process. The high yield and the ease of hydration of Fiber III are due to the content of polysaccharides-not-cellulose. These substances are proven to be present by the said process of extracting with strong caustic solution in making the alpha cellulose. The common paper-making pulps, such as commercial sulfite pulps, do not retain these polysaccharides to such degree and such commercial pulps do not yield such large amounts of polysaccharides in comparable processing to form alpha celluloses.

The properties of Fiber III which are of interest in connection with its usefulness as a paper-making stock are summarized in the following table, corresponding data for a commercial unbleached sulfite aspen fiber being included for purposes of comparison.

Table V tion is substantially entirely an action of dissolution not consuming sodium hydroxide as a reagent. For standardization purposes, the treatment is carried out for approximately one hour. Application of heat is preferably avoided, and the preferred temperature is 20 C. for standardization. The stronger caustic soda solution used in the extraction step tends to alter the cellulose as the temperature increases, and to minimize such alteration, and still effect the desired extraction, applied heat is avoided. However, where the utility of the resulting fiber may be such as to employ the form of cellulose effected by such alteration, any suitable temperature may be chosen for the desired result.

When the extraction has run its course, the fiber residue is separated from the liquor, and the latter may be fortified by adding sodium hydroxide for use of the fortified liquor in a like extraction on Fiber III, thereby to build up a content of extractives. The need for replacement results largely from mechanical loss, including retention of caustic soda by the fiber residue in the separation. In the case of 4% consistency using a 7% strength of caustic soda, the amount replaced is approximately 10% of the original amount.

Recycling with fortified solution on additional quantities PHYSICAL PROPERTIES OF ASPENEFIBERS AND PAPER COMMERCIAL UNBLEAGHED SULFITE ASPEN FIBER (YIELD BY 38%) Clark Slowness Apparent Tearing szrars asst Rese- Esaizs I l 51S ency s. ream ance (Sm) 24ggeggessh m Percent Percent Hydration 1 17 85. 4 20. 81 15 80 0 86 0 84 0 65 0 64 0 67 0 65 V. H. 65 V. H.

27 65.8 14. 29 12 41 0 154 48. 7 25.00 71 63 O 502 50. 7 27. 78 82 63 S 1,140 25. 4 30. 93 H 2, 130 17.3 31. 25 69 57 V. H.

NORMAL ASPLUND ASPEN FIBER III (YIELD 53%) 14. 71 15 47 0 20. 83 68 115 0 22. 22 84 1-23 0 22. 22 103 125 0 24. 39 108 107 0 26. 32 122 117 V. S. 27. 78 120 110 S 29.41 127 96 H 30. 30 129 6%} V. H.

1 As indicated by noting the appearance of blisters when subjecting the sample to an V. S., S, H, and V. 11., designate respectively: very slight, slight, high and very high.

Description of Step IV As pointed out hereinabove, Fiber III produced by the process of the invention may be applied to the production of a further quantity of non-cellulosic extractives and of chemical (alpha) cellulose, or it may be used as fiber in the manufacture of paper. When used for the production of a further quantity of non-cellulosic extractives and of chemical cellulose, the Fiber III produced as described above may be washed with water, largely for removal of adherent lignin retained from Extract III, and then extracted with a solution of sodium hydroxide of strength considerably greater than that used in Step III. This treatment may be generally designated as Step IV. This extraction may be carried out, for example, by treating the fiber with a solution having a strength within the range from 0.4% to 10%. Where the strength of the sodium hydroxide solution is 7%, and the fiber consistency of the extraction mass is 4% for the purpose of easy manipulation, the usage of sodium hydroxide is approximately 175% by weight of Fiber III ,(dry basis). This extraci of Fiber III may be carried on beneficially up to about 8 extracts for the conditions given. The fiber extract may then be processed for the separation of the extractives, which are largely polysaccharides-other-than-cellulose. This may be eifected by dilution with alcohol, for example, two volumes of methyl alcohol for one volume of recycled liquor. Such dilution precipitates polysaccharides which vary from pentoses to hexoses, depending largely upon the original wood employed. The precipitate is commonly a pure white substance and is easily removed by filtration.

The cellulosic residue from this strong caustic extraction of Fiber III is of a grade suitable for use as chemical cellulose, or alpha cellulose. It is produced in yields which are substantially higher than are possible by the more vigorous and less carefully controlled processes of the prior art. Thus, in the case of aspen, yields of chemical cellulose of the order of about 41.5% to 43.6%, based upon the weight of the original wood substance, are obtainable by the process of the invention. as carried out 19 :in the-examples already given. This is a considerable increase over the yields of about produced by the prior art processes.

SUMMARY Each -of the products obtained by this invention has .many developed and potential industrial uses. Cellulosic fiber residue, Fiber 111, may be used as is, or may be used as a .raw material to be processed further for the production of better grades of papermaking fiber, i. e., technical cellulose, and also for the production of chemical cellulose, or alpha cellulose. When the raw lignocellulose material is sawdust, hog fuel, or similar comminuted material, .the cellulosic product corresponding to JFiber III is :useful where a non-felting cellulosic fibrous product is desired.

The extracted substances likewise have important uses. 'Thelignins, for example, may be used in the manufacture of plastic clad plywood, impregnated papers, the tanning of leather, and as reagents for the recovery of metals from dilute solutions of metal salts. The polysaccharides obtainable by the process of the invention may be used, for example, as humectants and crystallization controllers, and may be fermented or otherwise treated to form other valuable products. Both the lignin and the polysaccharide extracts may be utilized as raw materials for the preparation of valuable organic compounds, as by controlled oxidation processes.

The present invention permits on a commercial economic scale the separation of lignins and polysaccharides from the same solution. The process also results in the production of a cellulose residue without loss of the valuable lignins and polysaccharides-other-than-cellulose products, since, as has been described herein, the procedure is such as to recover substantially all of the original lignocellulose substances. Since the operating conditions and the concentration of the reagent used are relatively mild, the procedure does not drastically change the chemical constitution of the wood substance beyond the changes required for enabling separation of the chemical constituents. On the other hand, the extracted substances are obtained in forms approaching, if not almost identical with, the forms in which they are found in the wood itself. The chemical reactivity and,

therefore, the usefulness of the extracted substances 'is far greater than the reactivity of corresponding substances obtained from liquors from conventional pulping processes that employ drastic cooking conditions. By using ditferent woods and slightly varying the operating procedures, it is possible to produce a variety of products having a substantial range in properties so as to be useful for a diversity of purposes. These manifold advantages are achieved, furthermore, by a process which makes use of relatively inexpensive reagents and apparatus and does not require the use of pressure vessels and protracted cooking operations.

It is also apparent from a consideration of the flow plan that the process of the invention for the separation of the constituents of the alkaline extract obtained from the treatment with an alkaline reacting compound of an alkaline metal at Step III is flexible, and may be varied as desirable or necessary when processing different materials, especially different species of woods. Thus, although it is usually desirable to separate the total lignin content into specific component lignins, because of the difierences in properties of these lignins, it maybe desirable in certain instances, for example, to effect the total precipitation of the lignins of Extract III in a single step, as by acidifying the extract to a pH of 1.5 and effecting the necessary concentration.

All the various modifications that may be practiced within the spirit of the disclosure herein, and the novel products which may be obtained from the practice of the invention, are deemed included in the invention.

What is claimed is:

1. The process of treating comminuted lignocellulose raw material to produce a fibrous product and chemical products therefrom, which comprises the steps of reacting the lignocellulose material with from about 2.5 parts to 100 parts of an alkaline reacting compound of an alkali metal for each 100 parts oven dry fiber in the presence of water at atmospheric pressure and at a temperature in the range from room temperature to about 140 C., extracting with an aqueous solvent the soluble products of reaction of the lignocellulose material with said alkaline :reactingcompound of an alkali metal, separatingthe extractives from the lignocellulose material to obtain a fibrous residue as a first product, treating the fibrous residue of said lignocellulose material with an alkali metal hypochlorite reagent having an equivalency of from 35 parts to parts sodium hydroxide for each parts by weight'dry fiber, extracting with an aqueous solvent the soluble products of reaction of said fibrous residue with said alkali metal hypochlorite reagent, separating the extractives from said fibrous residue to obtain the fibrous residue as a second product, treating the fibrous product of the last mentioned extraction and separation steps with an alkaline reacting compound of an alkali metal in the presence of water at a concentration of fromabout 0.4% to about 10% at atmospheric pressure and at a temperature in the range from room temperature to about C., extracting with an aqueous solvent the soluble products of said last named reaction, separating the fibrous material remaining from said last named extraction step to obtain a fibrous residue as a third product, and to provide a residual solution of said .last named reaction products.

2. The process defined in claim 1 together with the further steps of processing said 'last named solution to separate therefrom the lignin content as an intermediate product or products .and to leave as a last product a solution containing other organics including polysaccharides.

-3. The ;process of treating comminuted lignocellulose .raw .material to produce a fibrous product and chemical products therefrom, which comprises the steps of reacting the lignocellulose material with from about 2.5 parts :to 100 parts of an alkaline reacting compound of an alkali metal for each '100 ,parts oven dry fiber in the presence of water at atmospheric pressure and at a temperature in the range from room temperature to about 140 'C., extracting with an aqueous solvent the soluble products of reaction of the lignocellulose material with said alkaline reacting compound of an alkali metal, separating the extractives from the lignocellulose material to obtain a fibrous residue as a first product, treating the fibrous residue of said lignocellulose material with an alkali metal .hypochlorite reagent having an equivalency of from 3.5 parts to :80 parts sodium hydroxide for each 100 parts .by weight dry fiber, extracting with an aqueous solvent the :soluble products of reaction of said fibrous residue with said alkali metal hypochlorite reagent, separating the extractives from said fibrous residue to obtain the fibrous residue as a :second product, treating the fibrous product of the last mentioned extraction and separation steps with an alkaline reacting compound of an alkali metal in the presence of water at a concentration of from about 0.4% to about 10% at atmospheric pressure and at a temperature in the range from room temperature to about 140 'C., extracting with an aqueous solvent the soluble products of said last named reaction, separating the fibrous material remaining from said last named extraction step to obtain a fibrous residue as a third product, adding to the solution provided by said last mentioned aqueous solvent an acid having an ionizat-ion potential sufficient to bring the pH to about 1.5, thereby precipitating a lignin material, and separating the precipitated lignin to obtain the same as a fourth product and to leave a residual liquor.

4. The process of treating comminuted lignocellulose raw material to produce a fibrous product and chemical products therefrom, which comprises the steps of treating the lignocellulose material with from about 2.5 parts to 100 parts of an alkaline reacting compound of an alkali metal for each 100 parts oven dry fiber in the presence of water at atmospheric pressure and at a temperature in the range .from .room temperature to about 140 C., extracting with an aqueous solvent the soluble products of reaction of the lignocellulose material with said alkaline reacting compound of an alkali metal, separating the extractives from the lignocellulose material to obtain a fibrous residue as a first product, treating the fibrous residue of said lignocellulose material with an alkali metal hypochlorite reagent having an equivalency of from 35 parts to 80 parts sodium hydroxide for each 100 parts by weight dry fiber, extracting with an aqueous solvent the soluble products of reaction of said fibrous residue with said alkali metal hypochlorite reagent, separating the extractives from said fibrous residue to obtain the fibrous residue as a second product, reacting the fibrous product of the last mentioned extraction and separation steps with an alkaline reacting compound of an alkali metal in the presence of water at a concentration of from about 0.4% to about at atmospheric pressure and at a temperature in the range from room temperature to about 140 C., extracting with an aqueous solvent the soluble products of said last named reaction, separating the fibrous material remaining from said last named extraction step to obtain the same as a third product, adding to the solution provided by said last mentioned aqueous solvent an acid having an ionization potential suflicient to bring the pH to about 7, increasing the concentration thereof to the precipitation point of lignin when the solution is cooled, cooling said solution and separating the precipitated lignin as a fourth product and to leave a residual liquor.

5. The process defined in claim 4, together with the further steps of adding to the said residual liquor an acid having an ionization potential sufiicient to bring the pH to values between about 7 and about 1.5 at which lignin is precipitated, and separating said lignin precipitate from said liquor to recover the same as a fifth product.

6. The process defined in claim 4, together with the further steps of acidifying the said residual liquor by the addition thereto of an acid having an ionization potential sufficient to bring the liquor to a pH of 1.5, thereby causing the precipitation of lignin, and separating the lignin from the resulting liquor.

7. The process defined in claim 1, together with the further steps of acidifying the said resulting solution by the addition thereto in successive stages of an acid having an ionization potential sufiicient to reduce the pH value of said solution at each successive stage in the range from 7 to 1.5, and separating the lignin materials which precipitate from said solution at each successive stage.

8. The invention as defined in claim 3, together with the further steps of adding to the residual liquor an alkaline reacting material to raise the pH of said liquor to an equilibrium value, thereby precipitating the inorganic content of said liquor, and separating the precipitated inorganic content from the treated liquor, whereby to pro vide a liquor concentrate of organics including polysaccharides-other-than-cellulose.

9. The process defined in claim 1, together with the further steps of acidifying with sulfuric acid the said residual solution to a pH of 1.5 to cause the precipitation of all its lignin content, separating the lignin as precipitated to recover the same as a fourth product, adding to the solution remaining after the removal of said lignin an alkaline earth metal compound with the negative radical being selected from the group consisting of oxides, hydroxides and carbonates to raise the pH thereof to an equilibrium value thereby precipitating alkaline-earth metal sulfate, and separating the alkaline-earth metal sulfate from said solution, whereby to provide a liquid concentrate of organics including polysaccharides-other-thancellulose.

10. The process defined in claim 1 together with the further steps of treating the fibrous material obtained as a third product with an aqueous solution of sodium hydroxide having a strength in the range from 0.4% to 10%, whereby to render water soluble and to extract polysaccharides-other-than-cellulose which existed as water insolubles in said material before said treatment.

11. The method which comprises reacting at atmospheric pressure the system: lignocellulose in defibered form, Water and alkali metal hydroxide: said lignocellulose containing substantially all of the substance of the water-insoluble content of the natural lignocellulose of its origin, and constitutionally consisting primarily of cellulose, lignin and other organics having a substantial content of polysaccharides-other-than-cellulose, said three constituents being present in mutual ratios in the range of contents from those characterizing the said lignocellulose in natural form to those characterizing the said Water-insoluble content of said lignocellulose in natural form; in which system the alkali metal hydroxide is present in amount by weight in the range from 2.5 to 100 parts calculated as NaOH per 100 parts of oven dry lignocellulose, and the reaction is substantially completed to an equilibrium condition between the spent liquid and the fiber-form residue of the system at a reaction temperature in the range from room temperature to about point of lignin, and

140' C.; separating the fibrous residue remaining from dilute alkali metal hypochlorite solution in quantity up to about parts of sodium hydroxide equivalent of the hypochlorite salt for parts by weight of said fibrous residue, separating the fibrous product from the hypochlorite solution, subjecting the fibrous product to the action of a dilute solution in water of alkali metal hydroxide, said action being efiected at the boiling temperature of the solution and at atmospheric pressure for a time substantially to exhaust the potency of the liquor with respect to extraction of the fibers being treated thereby, separating the fibrous residue of said fiber product from the last named solution, adding acid to said solution in a quantity sufiicient to reduce its pH and cause the precipitation of its lignin content, and separating lignin from the solution.

12. The method which comprises reacting at atmospheric pressure the system: lignocellulose in defibered form, water and alkali metal hydroxide: said lignocellulose containing substantially all of the substance of the water-insoluble content of the natural lignocellulose of its origin, and constitutionally consisting primarily of cellulose, lignin and other organics having a substantial content of polysaccharides-other-thair-cellulose, said three constituents being present in mutual ratios in the range of contents from those characterizing the said lignocellulose in natural form to those characterizing the said water-insoluble content of said lignocellulose in'natural form; in which system the alkali metal hydroxide is present in amount by weight in the range from 2.5 to 100 parts calculated as NaOH per 100 parts of oven dry lignocellulose, and the reaction is substantially completed to an equilibrium condition between the spent liquid and the fiber-form residue of the system at a reaction temperature in the range from room temperature to about C.; separating the fibrous residue remaining from said reaction from the dissolved water-soluble materials, subjecting the said fibrous residue to the action of a dilute alkali metal hypochlorite solution in quantity up to about 80 parts of sodium hydroxide equivalent of the hypochlorite salt for 100 parts by weight of said fibrous residue, separating the fibrous product from the hypochlorite solution, subjecting the fibrous product to the action of a dilute solution in water of alkali metal hydroxide, said action being effected at the boiling temperature of the solution and at atmospheric pressure for a time substantially to exhaust the potency of the liquor with respect to extraction of the fibers being treated thereby, separating the fibrous residue of said fiber prodnot from the last named solution, neutralizing the treating liquor to pH 7 by the addition of an acid and increasing the concentration thereof to the precipitation separating precipitated lignin from the residual liquid.

13. The method of claim 12 together with the further steps of acidifying the said residual liquid to any pH between 7 and 1.5, at which lignin is precipitated, steam distilling the acidified liquor to remove volatile acids, and separating any precipitated lignin from the acidified and distilled liquor.

14. The method of claim 12 together with the further steps of acidifying the said residual liquid to any pH between 7 and 1.5 at which lignin is precipitated, and separating lignin from the acidified liquor.

15. The method of claim 12 together with the further steps of acidifying the said residual liquid by adding an inorganic compound having the HSO4 radical to any pH between 7 and 1.5, at which lignin is precipitated, steam distilling the liquor, separating any precipitated lignin from the acidified and distilled liquor, adding a compound selected from the group consisting of CaO, Ca(OH)2 and CaCOa to the liquor to substantial neutrality whereby to form and precipitate calcium sulfate, and separating the calcium sulfate from the liquor, whereby to provide a liquid concentrate of organics including polysaccharides-other-than-cellulose.

16. The method which comprises reacting at atmospheric pressure the system: lignocellulose in defibered form, water and alkali metal hydroxide: said lignocellulose containing substantially all of the substance of the water-insoluble content of the natural lignocellulose of its origin, and constitutionally consisting primarily of celu lulose, lignin and other organics having a substantial content of polysaccharides-other-than-cellulose, said three constituents being present in mutual ratios in the range of contents from those characterizing the said lignocellulose in natural form to those characterizing the said water-insoluble content of said lignocellulose in natural i form; in which system the alkali metal hydroxide is present in amount by weight in the range from 2.5 to 100 parts calculated as NaOH per 100 parts of oven dry lignocellulose, and the reaction is substantially completed to an equilibrium condition betwen the spent liquid and the fiber-form residue of the system at a reaction temperature in the range from room temperature to about 140 C.; separating the fibrous residue remaining from said reaction from the dissolved water-soluble materials,

subjecting the said fibrous residue to the action of a substantially to exhaust the potency of the liquor with I respect to extraction of the fibers being treated thereby,

separating the fibrous residue of said fiber product from the last named solution, and concentrating said solution to provide a syrup rich in polysaccharides-other-than-cellulose as one of the products of the last-mentioned separation.

17. The method which comprises reacting at atmospheric pressure the system: lignocellulose in defibered form, water and alkali metal hydroxide: said lignocellulose containing substantially all of the substance of the water-insoluble content of the natural lignocellulose of its origin, and constitutionally consisting primarily of cellulose, lignin and other organics having a substantial content of polysaccharides-other-than-cellulose, said three constituents being present in mutual ratios in the range of contents from those characterizing the said lignocellulose in natural form to those characterizing the said water-insoluble content of said lignocellulose in natural form; in which system the alkali metal hydroxide is present in amount by weight in the range from 2.5 to 100 parts calculated as NaOH per 100 parts of oven dry lignocellulose, and the reaction is substantially completed to an equilibrium condition between the spent liquid and the fiber-form residue of the system at a reaction temperature in the range from room temperature to about 140 C.; separating the fibrous residue remaining from said reaction from the dissolved water-soluble materials, subjecting the said fibrous residue to the action of a dilute alkali metal hypochlorite solution in quantity up to about 80 parts of sodium hydroxide equivalent of the hypochlorite salt for 100 parts by weight of said fibrous residue, separating the fibrous product from the hypochlorite solution, subjecting the fibrous product to the action of a dilute solution in water of alkali metal hydroxide, said action being effected at the boiling temperature of the solution and at atmospheric pressure for a time substantially to exhaust the potency of the solution with respect to extraction of the fibers being treated thereby, separating the fibrous residue of said fiber product from the last named solution, and con centrating said solution to provide a syrup rich in polysaccharides-other-than-cellulose.

18. The method which comprises reacting at atmospheric pressure the system: lignocellulose in defibered form, water and alkali metal hydroxide: said lignocellulose containing substantially all of the substance of the water-insoluble content of the natural lignocellulose of its origin, and constitutionally consisting primarily of cellulose, lignin and other organics having a substantial content of polysaccharides-other-than-cellulose, said three constituents being present in mutual ratios in the range of contents from those characterizing the said lignocellulose in natural form to those characterizing the said water-insoluble content of said lignocellulose in natural form; in which system the alkali metal hydroxide is present in amount by weight in the range from 2.5 to 100 parts calculated as NaOH per 100 parts of oven dry lignocellulose, and the reaction is substantially completed to an equilibrium condition between the spent liquid and the fiber-form residue of the system at a reaction temperature in the range from room temperature to about 140 C.; separating the fibrous residue remaining from said reaction from the dissolved water-soluble materials, subjecting the said fibrous residue to the action of a dilute alkali metal hypochlorite solution in quantity up to about 80 parts of sodium hydroxide equivalent of the hypochlorite salt for 100 parts by weight of said fibrous residue, separating the fibrous product from the hypochlorite solution, subjecting the fibrous product to the action of a dilute solution in water of alkali metal hydroxide, said action being effected at the boiling temperature of the solution and at atmospheric pressure for a time substantially to exhaust the potency of the solution with respect to extraction of the fibers being treated thereby, separating the fibrous residue of said fiber product from the last named solution, treating the residue of said fiber product to the action of an aqueous solution of sodium hydroxide having a strength in the range from 0.4% to 10%, whereby to solubilize lignin and polysaccharides-other-than-cellulose which exist as water-insolubles in said fiber before said treatment.

19. The process of treating comminuted lignocellulose raw material to form fiber and chemical products therefrom, which comprises the steps of reacting at atmospheric pressure and at a temperature in the range of from room temperature to about 140 C. the lignocellulose material with an alkaline reacting compound of an alkali metal in the presence of water, extracting with an essentially aqueous solvent the reaction products soluble therein, separating the solution thus obtained to leave the extracted fibrous residue, subjecting the said fibrous residue to the action of a dilute alkali metal hypochlorite solution in quantity from about 35 parts to about 80 parts sodium hydroxide equivalent of the hypochlorite salt for 100 parts by weight of said fibrous residue, extracting with an essentially aqueous solvent the reaction products soluble therein, separating the solution thus obtained to leave the extracted fibrous residue, subjecting the fibrous residue of said caustic-alkali and hypochlorite treatments to the action of an alkaline reacting compound of an alkali metal in the presence of water, said solution having a strength of from about 0.4% to about 10% caustic alkali, and separating the last named solution thus obtained to obtain a paper making fiber.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,541,058 Heritage et a1. Feb. 13, 1951 2,541,059 Heritage et a1. Feb. 13, 1951 2,541,127 Heritage et a1. Feb. 13, 1951 OTHER REFERENCES Wood Chemistry (Wise), published by Reinhold Publ. Corp., N. Y. C., 1946. 

1. THE PROCESS OF TREATING COMMINUTED LIGNOCELLULOSE RAW MATERIAL TO PRODUCE A FIBROUS PRODUCT AND CHEMICAL PRODUCTS THEREFROM, WHICH COMPRISES THE STEPS OF REACTING THE LONGNOCELLULOSE MATERIAL WITH FROM ABOUT 2.5 PARTS TO 100 PARTS OF AN ALKALINE REACTING COMPOUND OF AN ALKALI METAL FOR EACH 100 PARTS OVEN DRY FIBER IN THE PRESENCE OF WATER AT ATMOSPHERIC PRESSURE AND AT A TEMPERATURE IN THE RANGE FROM ROOM TEMPERATURE TO ABOUT 140* C., EXTRACTING WITH AN AQUEOUS SOLVENT THE SOLUBLE PRODUCTS OF REACTION OF THE LIGNOCELLULOSE MATERIAL WITH SAID ALKALINE REACTING COMPOUND OF AN ALKALI METAL, SEPARATING THE EXTRACTIVES FROM THE LIGNOCELLULOSE MATERIAL TO OBTAIN A FIBROUS RESIDUE AS A FIRST PRODUCT, TREATING THE FIBROUS RESIDUE OF SAID LIGNOCELLULOSE MATERIAL WITH AN ALKALI METAL HYPOCHLORITE REAGENT HAVING AN EQUIVALENCY OF FROM 35 PARTS TO 80 PARTS SODIUM HYDROXIDE FOR EACH 100 PARTS BY WEIGHT DRY FIBER, EXTRACTING WITH AN AQUEOUS SOLVENT THE SOLUBLE PRODUCTS OF REACTION OF SAID FIBROUS RESIDUE WITH SAID ALKALI METAL HYPOCHLORITE REAGENT, SEPARATING THE EXTRACTIVES FROM SAID FIBROUS RESIDUE TO OBTAIN THE FIBROUS RESIDUE AS A SECOND PRODUCT, TREATING THE FIBROUS PRODUCT OF THE LAST MENTIONED EXTRACTION AND SEPARATION STEPS WITH AN ALKALINE REACTING COMPOUND OF AN ALKALI METAL IN THE PRESENCE OF WATER AT A CONCENTRATION OF FROM ABOUT 0.4% TO ABOUT 10% AT ATMOSPHERIC PRESSURE AND AT A TEMPERATURE IN THE RANGE FROM ROOM TEMPERATURE TO ABOUT 140* C., EXTRACTING WITH AN AQUEOUS SOLVENT THE SOLUBLE PRODUCTS OF SAID LAST NAMED REACTION, SEPARATING THE FIBROUS MATERIAL MAINTAINING FROM SAID LAST NAMED EXTRACTION STEP TO OBTAIN A FIBROUS RESIDUE AS A THIRD PRODUCT, AND TO PROVIDE A RESIDUAL SOLUTION OF SAID LAST NAMED REACTION PRODUCTS. 